This application is based on patent application Ser. Nos. 2000-224550 filed Jul. 25, 2000 and 2000-224551 filed Jul. 25, 2000 in Japan, the content of which is incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to a composite deodorization method combining water molecule deodorization, ozone deodorization and ion deodorization methods, and a composite deodorization system, and to an ion deodorization system which ionizes the treated gas to negative ions and removes by adsorbing odor components to a photocatalyst panel thereby decomposing them by an oxidative decomposition reaction.
2. Description of the Related Art
Heretofore, as methods for deodorizing a gas containing odor components, there have been known a water molecule deodorization method, an ozone deodorization method, an ion deodorization method and the like. Each of these methods is for efficiently recovering odor components contained in the gas to achieve deodorization. The water deodorization method removes water in the gas thereby removing odor components dissolved in the water, the ozone deodorization method generates plasma ozone to decompose the odor components by oxidation thereby achieving deodorization. An air cleaner for removing odor components in a living room or the like using the ozone deodorization method is disclosed in, for example, Japanese Patent Application Laid-open No. 6-262098. According to the publication, it is described that air in the living room or the like is taken into the cleaner, deodorization and sterilization are performed by an ozone deodorization catalyst, and excess ozone is removed by an acid gas absorber.
The ion deodorization method is to ionize the gas to negative ions, absorb odor components in the gas to a photocatalyst, and decompose the odor components by oxidation. An air cleaner for removing odor components in a living room or the like using the ion deodorization method is disclosed in, for example, Japanese Patent Application Laid-open No. 3-109953. According to the publication, a method is described in which to a treated gas passing through a dust collection filter and a catalyst layer, corona discharge is used to ionize the gas to negative ions. These methods are to deodorize a treated gas of a predetermined amount in a closed space such as a living room or the like.
A photocatalytic action means that when oxygen or water vapor in the air contacts the photocatalyst, it changes into an active oxygen species by an optical energy, and harmful substances and active oxygen species repeat an oxidative decomposition reaction to decompose the harmful substances into water and carbon dioxide. For example, it is known that when interiors and exteriors are finished using a photocatalyst panel coated with a photocatalyst coating based on titanium oxide, staining-proof, sterilizing, mold-proof, and deodorization effects are obtained.
When performing air cleaning of a living room or the like utilizing the photocatalytic action, it is impossible to deodorize a predetermined amount of gas only by oxidative decomposition of odor components spontaneously adhering the photocatalyst. Then, a method is described in, for example, Japanese Patent Application Laid-open No. 11-60208, in which a photocatalyst panel provided with a photocatalyst coating of titanium oxide is irradiated with ultraviolet light to oxidize and reactivate the photocatalyst to promote the photocatalytic action. According to this publication, it is described that in ion and ozone generators having a needle-formed electrode and a cylindrical electrode, ultraviolet light is emitted from the needle-formed electrode and ion and ozone are generated to achieve deodorization. Further, a system to ionize the treated gas containing odor components to negative ions to cause odor components to forcedly absorb into the photocatalyst panel is described in, for example, Japanese Patent Application Laid-open No. 3-109953. According to this publication, a method is described in which a treated gas passing through a dust collection filter and a catalyst layer is negatively ionized using corona discharge. On the other hand, a method is known in which negative ions are emitted directly to the air in the treated gas. Of these, an electron radiator using an electron radiation needle is described in Japanese Patent Application Laid-open No. 9-232068.
On the other hand, in a fermentation system in which organic residues are treated to produce a compost, a large amount of gases containing odor components associated with aerobic fermentation are generated. When performing deodorization of large amounts of gas containing odor components, there has been a problem in that only by the water molecule deodorization method, only water-soluble odor components can be deodorized. Further, in the ozone deodorization method, in view of the global environment protection, in order to treat the generated ozone, an apparatus for treating a large amount of gas results in a cost increase. Further, there has been a problem in that only by the ion deodorization method, only odor components spontaneously adhering to the photocatalyst are oxidatively decomposed, and to deodorize a large amount of gas, photocatalyst of large surface area is required which makes the apparatus large-sized.
With an eye on the deodorization function in the ion deodorization method, only by installation of a photocatalyst panel, only odor components spontaneously adhering to the photocatalyst panel are oxidatively decomposed, and therefore it is impossible to forcedly deodorize a large amount of air containing odor components. Even when the photocatalyst panel is irradiated with ultraviolet light to promote the photocatalyst, the deodorization capacity is limited as far as with the photocatalyst panel of a constant surface area.
Then, it is performed that the treated gas is negatively ionized by corona discharge to cause odor components to adhere forcedly to the photocatalyst panel, however, since the method using corona discharge is low in negative ion production capacity, there has been a problem in that the capacity of forcedly adhering odor components to the photocatalyst panel is low. On the other hand, in the method using corona discharge, since ozone is generated, there is a problem in that the oxidative decomposition reaction of the photocatalyst is disturbed. Further, in view of the global environment protection, a treatment is necessary for preventing release of ozone out of the system which results in a large-sized deodorization system and an increased cost.
An object of the present invention is to provide a composite deodorization method in which ozone deodorization is performed after water molecule deodorization, and then ion deodorization is performed to efficiently deodorize a large amount of treated gas containing odor components and a system for the method.
Another object of the present invention is to provide an ion deodorization system in which negative ions are radiated directly to the treated gas to promote adherence of odor components to the photocatalyst so that in combination with promotion of the photocatalyst by ultraviolet radiation, a large amount of odor is efficiently removed.
The present invention which attains the above objects is characterized by comprising a water molecule deodorization step for removing water from a treated gas so that odor components dissolved in the water in the treated gas are removed; an ozone deodorization step for mixing the treated gas treated in the water molecule deodorization step with plasma ozone and oxidatively decomposing odor components contained in the treated gas; and an ion deodorization step for negatively ionizing the treated gas treated in the ozone deodorization step and adhering odor components contained in the treated gas for oxidative decomposition.
Further, the water molecule deodorization step is possible to include a radiation treatment step for decreasing temperature of the treated gas removed of odor components.
Still further, the ozone deodorization step is possible to include an ozone removing step for removing plasma ozone contained in the treated gas oxidatively decomposed of odor components.
Yet further, the present invention is characterized by comprising a first chamber having a gas introduction opening supplied with a treated gas, a second chamber communicating with the first chamber, and a third chamber communicating with the second chamber, wherein the first chamber includes a cooling panel for condensing water in the treated gas and a drain panel for discharging water drops condensed on the cooling panel along with odor components dissolved in water in the treated gas, and the second chamber includes an ozone generator for generating plasma ozone and a reaction chamber for oxidatively decomposing odor components contained in the treated gas by the plasma ozone generated by the ozone generator, and the third chamber includes an electron radiator for negatively ionizing the treated gas, a photocatalyst panel for adsorbing and oxidatively decomposing odor components contained in the treated gas, and a gas discharge opening for discharging the treated gas. In addition, relative humidity of the treated gas treated by the cooling panel is lower than external humidity of the first chamber.
Further, the first chamber can include a heat radiation panel for decreasing temperature of the treated gas passed through the cooling panel. In addition, temperature of the treated gas treated by the heat radiation panel is lower than external temperature of the first chamber.
The first chamber and the second chamber are connected with a flow passage tube, and an ozone generator can be disposed at the connection position of the first chamber and the flow passage tube. Further, the second chamber can include an ozone removing filter for removing ozone contained in the treated gas.
The electron radiator radiates electrons directly to the space for negatively ionizing the treated gas. Further, the third chamber can include an ultraviolet irradiator for irradiating ultraviolet light to the photocatalyst panel.
Yet further, the treated gas is a gas generated during aerobic fermentation of organic residue.
Yet further, the present invention is an ion deodorization system for absorbing odor components contained in the treated gas and removing the odor components by an oxidative decomposition reaction, characterized by comprising an electron radiator for negatively ionizing the treated gas, and an ultraviolet irradiator for irradiating ultraviolet light to the photocatalyst panel. In addition, the electron radiator radiates electrons directly to the space for negatively ionizing the treated gas.
Yet further, the present invention is an ion deodorization system for absorbing odor components contained in the treated gas and removing the odor components by an oxidative decomposition reaction, characterized by comprising an electron radiator for negatively ionizing the treated gas, wherein the electron radiator radiates electrons directly to the space, thereby negatively ionizing the treated gas.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.